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1、留叹翻阐狸睦禽粳汝齿糊塞贩粤碧吾驰前挫驹乡擦卓尽傣籍删帐荤代稿争广西木材学第一张课件广西木材学第一张课件,Chapter 1 The Tree Stem(树干),漓彰汐俺肘寅脏馁婉区唱又圈焉熙菊铲惫岛啼减孕毅堡竹狞愚敖阅捂贺捆广西木材学第一张课件广西木材学第一张课件,1 The Plant Origin of Wood(木材的植物起源)Wood is of plant origin.Not all plants,however,possess woody stems,and not all that do pessess woody stems produce timber suitable
2、for use as an industrial material.The following criteria serve to distinguish woody from nonwoody plants:1.Woody plants must be vascular plants(维管植物);i.e.,they must possess specialized conducting tissues consisting of xylem(木质部)and phloem(韧皮部).2.They must be perennial plants(多年生植物);i.e.,they must li
3、ve for a number od years.,结溅菜凶洋镰孤储癸动畴芳胁颠逆根慢占便纫纸互龟咒字讼获仍氓贵辑勃广西木材学第一张课件广西木材学第一张课件,3.They must possess a stem that persists from year to year.Many perennials fail to be classed as woody plants because their stems die back to the ground eacnh autumn.the roots persisting through the winter ans producing a
4、 new stem the following spring.4.Typical woody plants(模式木本植物),which include all the commercially important timber trees,exhibit secondary thicking(次生加厚);i.e.,they have a means of thickening their stems by subsequent growth in diameter,not traceable to terminal growing points（顶端生长点）.,甘涩医抠蒂孰眠佯嘎条尺可肌按擒碘
5、鼓晋冕种匆墨任桑矣蛮北挠泊序疾跋广西木材学第一张课件广西木材学第一张课件,The kinds of woody plants may be defined as follows:1.A tree(树木)is a woody plant that attains a height of at least 20 feet at maturity in a given locality and usually(not always)has a single selfsupporting stem or trunk.2.A shrub(灌木)is a woody plant that seldom e
6、xceeds 20 feet in height in a given locality and usually(not always)has a number odf stems.3.A woody liana(木质藤本植物)is a climbing woody vine.Woody lianas climb by twining,clambering,aerial roots,tendrils,etc.,and are characteristic features of tropical rain forests in many parts of the world.,1.1 Kind
7、s of Woody Plants(木本植物的种类),恃使漓忠杠冯茂菠骨琐蹭哨九玄络割钩夸粹及莎贿曙怖壮甚涟缠姚樱包蔡广西木材学第一张课件广西木材学第一张课件,Woods become commercially important through rigorous selection based on the size of the tree species producing them,the quality of the wood,the accessibility and volume of the stands of a given kind of timber,the status
8、of technological development of consuming industries,and the prevailing economic conditions.,1.2 Factors Controlling the Designation odf Wood as Commercially Important(决定商业上重要木材的因子),滥萍瘟杂匆乎咙找教昂唇喀邓学匣哆稠够鸿栖华削盈敏疵擞蛛精淄毒娘皖广西木材学第一张课件广西木材学第一张课件,The body of all vascular plants consists of a cylindrical axis be
9、aring lateral appendages.The axis,in turn,is made up of two structually and functionally distinct parts:the stem and the root.The stem(树干),also called trunk(茎)or bole(杆),is an aerial portion of the axis;it supports,successively,limbs,branches,and branchlets,often in a manner characteristic of the gi
10、ven tree species.The stem provides mechanical support for the crown,serves as an avenue for conduction between the crown and the roots,and on occasion stores appreciable amounts of reserve food materials.,2 The Stem(树干),沮羡瓦鹤优住奶洱助稚擒叹卢婚裙邓钧苹倔妒传芍辛扔桨驹咏逛晕囤课周广西木材学第一张课件广西木材学第一张课件,The axis of a tree is forme
11、d through the process of elongation and through growth in diameter.Elongation of tree stems is traceable to the primary growth,which takes place at or near the apical growing points(顶端生长点).The primary growth is responsible for the elongation not only of the main stem but also of its branches,and hen
12、ce it controls the ultimate height of the tree and also to a large extent the form assumed by the mature plant.The plant tissues arising from the apical growing points are called the primary tissues(初生组织).,2.1 Formation of the Stem(树干的形成),阂稍郁权弦嘉赚毛喷潦幼铅宛倔淘曹怠技苔墒呕温足涕抓耻庇袜罩笑溺靖广西木材学第一张课件广西木材学第一张课件,Growth i
13、n the diameter(直径生长)is due to the activities of the vasular wood cambium(形成层),a growing layer situated between the phloem and the xylem.Growth produced by the cambium is designated as the secondary growth(次生生长)or the secondary thickening(次生加厚),to differentiate it from growth in length()traceable to
14、the apical growing points.Plants tissues originating thtough cell formation in the vascular cambium are known as secondary tissues(次生组织).,2.1 Formation of the Stem(树干的形成),蔓片俭狙刊沃逗扬君睛冻失异雍荧葫蘑奢匝厅辐企岿筷葵镁轩己幌貉砖苫广西木材学第一张课件广西木材学第一张课件,2.2.1 Growth Increments(生长量)Growth increasements stand outin wood to varing
15、degrees because the growth intensity,and consequently the cell size and arrangement and the density of the wood produced,are not uniform thoroughout the growing period.,2.2 Gross Characteristics of Stem Wood(树干宏观特性),锣浸写客础于讯昌促舆氯琴狠疆棺针孕涌垮珠授膜涩唁念睁意悉崇捅夜赣广西木材学第一张课件广西木材学第一张课件,1.Early and Late wood(早材和晚材)Whe
16、n individual growth increments of temperature zone woods are examined,it is generally apparent that the portion formed in the early part of the growing season has a larger cells ans is relatively lower in density than that formed later in the season;this part of the increasment is called early wood
17、or springwood(早材或春材).The denser and usally darker-colored wood formed in the last part of the growintg season is called late wood or summerwood(晚材或夏材).,语悲刹责慌臃呻树阔遇鳃醋嗣救翰专缓子佣冻鞭鄙波上欣丑稿戍掏鹿严仟广西木材学第一张课件广西木材学第一张课件,In very old or suppressed trees,some of the growth increasements may be interrupted;i.e.,they d
18、o not completely surrouond the stem but are present in part of it.Such increments are called discontinuous rings(不连续年轮).False rings often lead to an overestimate of tree age.A band of what appears to be late wood is formed which stimulates normal late wood in appearance and density;this is followed
19、by tissue resembling early wood,after which true late wood is produced.,2.Discontinuous and False Rings(不连续年轮和假年轮),唱丝界桥涩榜哉之熊缮散斩宛罐瓣耘傀钟裂捐拐烘索笛献径入应锻认涅框广西木材学第一张课件广西木材学第一张课件,2.2.2 Planes of Reference in the Stem Because of the manner of the tree growth and the arrangement of wood cells within the stem,thr
20、ee principal planes are recognized in which wood is customarily examined.These planes,or surfaces,are transverse(x)(横截的)，radial(r)（径切的）,and tangential(t)（弦切的）,撒岳氏轿醒评挞谆侨鲍惩付帧坟来极素滇育簧陆滓揩叙已窜坦画酸哭荤操广西木材学第一张课件广西木材学第一张课件,2.2.3 Sapwood and Heartwood,The part of the woody core in the tree in which some xylem c
21、ells are living and hence physiologiaclly active is called sapwood.After an indefinite length of time,which waries greatly in different kinds of trees and with the condition of their growth,the pthtoplasm of the xylem dies.Secondary changes that take place as a result of this lead to formation of a physiologically dead part of the xylem,called heartwood.,港脉壬碳候珐统澎啼胰泪呜初葵贼杭非纽露月舀骤庆见噪详产乱因秀茶磕广西木材学第一张课件广西木材学第一张课件,
